package com.rfsp.common.jwt;

import org.apache.shiro.authz.UnauthorizedException;
import org.apache.shiro.web.filter.authc.BasicHttpAuthenticationFilter;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.RequestMethod;

import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.URLEncoder;

/**
 * @author zhangchao
 * @create 2020-07-12 15:56
 * @desc
 **/
public class JwtFilter extends BasicHttpAuthenticationFilter {


    /**
     * 这里我们详细说明下为什么最终返回的都是true，即允许访问
     * 例如我们提供一个地址 GET /article
     * 登入用户和游客看到的内容是不同的
     * 如果在这里返回了false，请求会被直接拦截，用户看不到任何东西
     * 所以我们在这里返回true，Controller中可以通过 subject.isAuthenticated() 来判断用户是否登入
     * 如果有些资源只有登入用户才能访问，我们只需要在方法上面加上 @RequiresAuthentication 注解即可
     * 但是这样做有一个缺点，就是不能够对GET,POST等请求进行分别过滤鉴权(因为我们重写了官方的方法)，但实际上对应用影响不大

     * @param request
     * @param response
     * @param mappedValue
     * @return
     */
    /*public boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) {
        try {
            executeLogin(request, response);
            return true;
//            Subject subject = SecurityUtils.getSubject();
//            String url =  WebUtils.getPathWithinApplication(WebUtils.toHttp(request));
//            return subject.isPermitted(url);
        } catch (Exception e) {
            return false;
        }
    }*/

    @Override
    protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) throws UnauthorizedException {
        //判断请求的请求头是否带上 "Token"
        if (isLoginAttempt(request, response)) {
            executeLogin(request, response);
            //如果存在，则进入 executeLogin 方法执行登入，检查 token 是否正确
            /*try {
                executeLogin(request, response);
                return true;
            }catch (Exception e) {
                //token 错误
                responseError(response, e.getMessage());
            }*/
        }
        //如果请求头不存在 Token，则可能是执行登陆操作或者是游客状态访问，无需检查 token，直接返回 true
        return true;
    }

    /**
     * 判断用户是否想要登入。
     * 检测header里面是否包含Authorization字段即可
     */
    protected boolean isLoginAttempt(ServletRequest request, ServletResponse response) {
        HttpServletRequest req = (HttpServletRequest) request;
        String authorization = req.getHeader(JwtUtil.TOKEN_HEADER);
        return authorization != null && !"".equals(authorization);
    }

    /**
     *
     */
    protected boolean executeLogin(ServletRequest servletRequest, ServletResponse servletResponse) throws UnauthorizedException {

        HttpServletRequest request = (HttpServletRequest) servletRequest;

        String token = request.getHeader(JwtUtil.TOKEN_HEADER);

        JwtToken jwtToken = new JwtToken(token);
        // 提交给realm进行登入，如果错误他会抛出异常并被捕获
        getSubject(request, servletResponse).login(jwtToken);
        // 如果没有抛出异常则代表登入成功，返回true
        return true;
    }




    /**
     * 将非法请求跳转到 /unauthorized/**
     */
    private void responseError(ServletResponse response, String message) {
        try {
            HttpServletResponse httpServletResponse = (HttpServletResponse) response;
            //设置编码，否则中文字符在重定向时会变为空字符串
            message = URLEncoder.encode(message, "UTF-8");
            //httpServletResponse.sendRedirect("/app1/unauthentication/" + message);
            httpServletResponse.sendRedirect("/app1/unauthorization");
        } catch (IOException e) {
//            logger.error(e.getMessage());
        }
    }


    /**
     * 对跨域提供支持
     */
    @Override
    protected boolean preHandle(ServletRequest request, ServletResponse response) throws Exception {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        HttpServletResponse httpServletResponse = (HttpServletResponse) response;


        httpServletResponse.setHeader("Access-control-Allow-Origin", httpServletRequest.getHeader("Origin"));
        httpServletResponse.setHeader("Access-Control-Allow-Methods", "GET,POST,OPTIONS,PUT,DELETE");
        httpServletResponse.setHeader("Access-Control-Allow-Headers", httpServletRequest.getHeader("Access-Control-Request-Headers"));

        // 跨域时会首先发送一个option请求，这里我们给option请求直接返回正常状态
        if (httpServletRequest.getMethod().equals(RequestMethod.OPTIONS.name())) {
            httpServletResponse.setStatus(HttpStatus.OK.value());
            return false;
        }

        return super.preHandle(request, response);
    }
}
